Almost all the resource URLs in our CSS file are mangled in a similar way. After a lot of head scratching, it turns out that the URLs are longer than ResourceImpl$ValueExpressionFilterInputStream is prepared to handle:

For us, setting the "unread" buffer to a higher number than 255 appears to solve the issue. Perhaps this could be done a different way to account for longer URLs or at least made configurable if someone needs to adjust it.

Issue Links

is cloned as

MYFACES-3414MyFaces ResourceImpl$ValueExpressionFilterInputStream does not handle resolving long URLs